ColorSync Utility to the Rescue And, in fact, there is The trick is to create a new compression profile using your native ‘ColorSync’ utility. You can duplicate Apple’s standard ‘Reduce File Size’ filter there and easily tinker with the settings of your new filter. ColorSync Utility to shrink PDF with custom filters from Preview Quartz Filter - colorsync-filters.md. ColorSync is an Apple utility that has been around for years and is really designed for users who have some knowledge of color and color management. However, there are some features that can be used by novices as well.

For some reason, every time I download a pdf file, my computer has started trying to open it with colorsync utility. I select the file, go to file, get info and it says open with 'none'. I switch it to preview and it will open. But when I try to change all for similar documents I get the following messsage:
An error occurred while changing the application that opens 'file name' because not enough information is available. Do you want to open 'file name' with Preview? Then it gives me a choice of cancel, don't update or update.
Doesn't seem to magtter which one I choose. I can now open that file, but next time I have a pdf file, the same thing happens and I have to go to the file menu to get it to open. This started fairly recently.
I have run disk utility, repair permissions.
I have run colorsync utility verify and it says all my profiles are correct. Any idea what causes this?
Thanks

What is ColorSync?
(confusing us) is My PEEVE!

ColorSync® is a registered trademark of Apple Computers.

'ColorSync Profile' = ICC Profile = 'ColorSpace'

I think the color confusion starts by using Apple's 'ColorSync' terminology to encompass 'color management':

ColorSync this..
ColorSync that..
ColorSync calibration..
ColorSync Profiles..

I will argue 'ColorSync Profile' is more accurately referred to as an 'ICC Profile' in the field of digital color management.

ColorSync is — merely — a Color Management System (CMS - CMM).
In the case of OS-X, ColorSync also includes an application 'ColorSync Utility.app' used to set up and repair ColorSync issues on the Mac.

Adobe (ACE), Heidelberg, Agfa, and Kodak CMS/CMMs are also individual Color Management Systems (CMS), Color Management Modules (CMM).

Read about BASIC THEORY HOW PROFILES WORK in color-managed applications.

See ColorSync ICC Profiles in action in your Safari, FireFox IE Web browsers.

Here is Apple'sReference Library ColorSync page at Apple.com.
For more on the ICCInternational Color Consortium www.color.org.

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LANGUAGE-TRANSLATION ANALOGY

Think of any Color Management System (CMS) as an interpreter of ICC profiles.
The CMS can speak all ICC–profiled languages.

Think of any ICC profile as the written language of each individual, SPECIFIC DEVICE (or ColorSpace) it represents.

Think of your specific monitor ICC profile (MonitorRGB) as an English speaker.

Think of your specific printer/paper/ink ICC profile (TargetICC) as a Spanish speaker.

Think of your Photoshop TaggedFile as a Japanese speaker.

'TaggedFile' represents the Embedded/Tagged colorspace of the open RGB or CMYK file.
If you are Embedding/Tagging your RGB files with 'Adobe (1998) RGB' for example:
TaggedFile = AdobeRGB = WorkingRGB

Further: Enabled Monitor ICC Profile = MonitorRGB

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Think of what the Color Management System does:

MonitorRGB < TaggedFile > TargetICC/CMYK

In other words:
TaggedFile is CONVERTED to MonitorRGB.
TaggedFile is CONVERTED to a specific TargetICC or CMYK.

Colorsync Utility Windows

The CMS takes Photoshop's TaggedFile, Converts (translates) it into MonitorRGB (and onto the screen). Cricket darts score sheet excel.

The CMS takes Photoshop's TaggedFile, Converts (translates) it into Specific printer/paper/ink ICC (and onto the print).

Colorsync Utility Download

Without an interpreter, a CMS — our eyes are explaining our color to an English speaker (MonitorRGB) who explains it to a Japanese speaker (TaggedFile) who explains it to a Spanish speaker (Specific printer/paper/ink) — a screen–to–print match is not gonna happen. Quantstudio viia 7 software mac os.

See embedded ICC Profiles in action Color Management tutorial
Includes on-line demonstrations of Tagged and UnTagged sRGB, AdobeRGB, AppleRGB
Monitor calibrating and profiling tips, 2.2 gamma, 1.8 Mac gamma, D65 6500 degrees Kelvin

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Adobe Photoshop is a color–managed application.

As a color–managed application:
Photoshop's Color Management SystemConverts a Tagged File into MonitorRGB (the monitor's 'calibrated' colorspace) and thereby displays the tagged file's 'true color' through the monitor's 'calibrated' colorspace.

In other words, for example:
In a color–managed application like Photoshop — the enabled Color Management System (CMS):

CMS Converts TaggedFile to MonitorRGB (and onto your screen).
• If the monitor ICC profile is not accurate, the screen will not be accurate.